Nuclear transport of trimeric assembly intermediates exerts a morphogenetic control on the icosahedral parvovirus capsid
Nuclear transport of trimeric assembly intermediates exerts a morphogenetic control on the icosahedral parvovirus capsid
复制标题
DOI：
10.1016/j.jmb.2006.01.019
复制
发表时间：
2006-03-31
影响因子：
5.6
通讯作者：
Almendral, JM
中科院分区：
文献类型：
--
作者：
Riolobos, L;Reguera, J;Almendral, JM
使用小鼠细小病毒（MVM）的核衣壳作为模型，研究了大分子实体的核运输和形态发生之间的联系。 VP1 (82 kDa) 和 VP2 (63 kDa) 蛋白以各自 1:5 的合成摩尔比形成 T=1 二十面体 MVM 衣壳，可以与二亚亚胺酸二甲酯共价交联成两种类型的寡聚组装体，这些组装体以化学计量存在于感染细胞提取物和纯化的病毒颗粒中。较大的物种含有 VP1，大小 (200 kDa) 相当于一个 VP1 和两个 VP2 亚基的异源三聚体。较小的物种仅含有 VP2，大小 (180 kDa) 相当于同源三聚体。在MVM衣壳中VP三聚体之间的界面处引入大量残基或截断涉及多种相互作用的侧链，产生了三聚体中间体的积累，这些中间体能够进行核易位，但不能进行衣壳组装。这些结果表明，MVM 的成熟是通过衣壳亚基的细胞质寡聚化成两种类型的三聚体来进行的，这些三聚体是能够跨核膜易位的组装中间体。一致：与这一结论一致，使先前鉴定的β链核定位基序失活的基本残基的突变，特别是不参与亚基间或亚基内的接触，导致两种类型的三聚体保留在细胞质中，没有其他组装中间体的证据。尽管一部分含有 VP1 的三聚体在 VP1 N 末端的常规核转运信号驱动下易位到细胞核中，但在不含 VP2 的三聚体不存在的情况下，它们的进一步组装产生了大分子量的无定形聚集体。因此，组装中间体的核运输化学计量可以对MVM衣壳等大分子复合物进行形态发生质量控制。 (c) 2006 Elsevier Ltd. 保留所有权利。
The connection between nuclear transport and morphogenesis of a large macromolecular entity has been investigated using the karyophylic capsid of the parvovirus minute virus of mice (MVM) as a model. The VP1 (82 kDa) and VP2 (63 kDa) proteins forming the T=1 icosahedral MVM capsid at the respective 1:5 molar ratio of synthesis, could be covalently cross-linked with dimethyl suberimidate into two types of oligomeric assemblies, which were present at stoichiometric amounts in infected cell extracts-and purified viral particles. The larger species contained VP1 and corresponded in size (200 kDa) to a heterotrimer of one VP1 and two VP2 subunits. The smaller species contained VP2 only and corresponded in size (180 kDa) to a homotrimer. The introduction of bulky residues or the truncation of side-chains involved in multiple interactions at the interfaces between trimers of VPs in the MVM capsid, produced the accumulation of trimeric intermediates that were competent in nuclear translocation but not in capsid assembly. These results indicate that MVM maturation proceeds by cytoplasmic oligomerization of the capsid subunits into two types of trimers, which are the assembly intermediates competent to translocate across the nuclear membrane. Consistent: with this conclusion, mutations at basic residues that inactivate a previously identified beta-stranded nuclear localization motif, which notably are not involved in inter or intra-subunit contacts, led to cytoplasmic retention of the two types of trimers, with no evidence for other assembly intermediates. Although a fraction of the VP1-containing trimers were translocated into the nucleus driven by the conventional nuclear transport signal of VP1 N terminus, their further assembly in the absence of the VP2-only trimers yielded large molecular mass amorphous aggregates. Therefore, the nuclear transport stoichiometry of assembly intermediates may exert a morphogenetic quality control on macromolecular complexes like the MVM capsid. (c) 2006 Elsevier Ltd. All rights reserved.